The deposition of cerumen or wax in or on active parts of hearing aids located in the ear canal (e.g. in-the-ear (ITE) or receiver-in-the-ear (RITE) parts of hearing instruments) is an issue that has to be dealt with. Wax protection in hearing aids is usually implemented by a barrel shaped insert at the tip of ITE-hearing aids or at the tip of the receiver unit in RITE-instruments. The insert typically has small holes to allow the sound to pass while the wax should be held back in the wax protection.
Hearing aids comprising an ITE-part comprising an ear mould typically comprise a vent to avoid or minimize occlusion effects due to the blocking of the ear canal by the mould. To prevent the vent from being blocked by wax, specific measures have to be taken.
WO 97/09864 A1 describes a hearing aid with a cerumen guard comprised of a rigid porous plastic plug adjacent to the exterior surface of the hearing aid shell. The individual cerumen guards may be inserted into the receiver outlet, the microphone inlet, or the vents of the hearing aid.
DE 39 33 584 A1 describes a wax filter of a porous material. The filter can cover receiver and vent outlets in combination or separately.
WO 02/078392 A2 deals with the manufacturing of a hearing aid housing that is individually matched to the shape of the auditory canal of a user, the hearing aid housing being produced with an integrated ventilation channel and possibly an acoustic output opening. Either or both of the acoustic output opening and the ventilation channel opening may be adapted to receive and hold an ear wax guard.
U.S. Pat. No. 4,987,597 describes an apparatus for closing an opening of a hearing aid or an ear adaptor for a hearing aid, particularly openings such as sound entry openings, sound exit openings and aeration openings utilizes a micro-porous membrane of an anti-adhesive material which is introduced into the respective opening. Preferably, the membrane is polytetrafluoroethylene material.
DE 8436783 U1 describes an in the ear hearing aid comprising openings for a speaker outlet as well as for a ventilation channel, which may be covered by a common lid functioning as a wax filter for both openings.